1. Field of the Invention
The invention relates to an arrangement for adjusting the pitch of a ship's propeller, and more particularly, for adjusting and locking the pitch of the ship's propeller.
2. Description of the Prior Art
Variable or adjustable pitch propellers for ships are well known in the prior art. The following are some examples of prior art:
U.S. Pat. No. 3,895,598 shows a ship propulsion unit which comprises a variable pitch propeller supported in a hub. A plurality of annular chambers are defined, through which pass a number of supply and return lines for several fluid pressure systems which lead to the propeller and a servo motor for adjusting the pitch of the propeller blades.
U.S. Pat. No. 4,142,829 relates to a compound remote control device for controlling the pitch of a variable-pitch propeller on a ship's drive mechanism while, at the same time, controlling the speed of the ship's engine, and provides a control mechanism for compound control under various control conditions, using one cam and a pressure-control valve cooperating therewith. With this control device, control of the speed of the aforesaid engine and the control of the pitch of the variable-pitch propeller are carried out by using air-pressure signals under various control conditions, that is, where the relationship of the various control air pressures in relation to the position of the control lever varies.
U.S. Pat. No. 4,229,141 shows a propeller comprising a hub having a rotating fitting mounted on the central end part thereof, which permits the passage therethrough of a fluid circulating within two conduits which pass longitudinally of the fitting. The fluid operates on opposite ends of an annular piston to impart thereto rectilinear movement, which in turn is transformed into rotation of the blades of the propeller, due to lugs extending from the piston and being eccentrically engaged with the blades. The hub of the propeller is completely free to turn without affecting the driving shaft. The assembly is positioned completely outside the stern of the ship.
Another example of the prior art is German Pat. No. DE-PS 878 906, which relates to an adjustable pitch propeller which can be adjusted and the setting maintained. All of the above-cited patents are incorporated herein by reference.